1.
Aim
To introduce research
regarding how the body and mind are inextricably linked, focusing on the
effects of exercise on brain development in humans.
2.
Intended audience
The general public as it
has far reaching consequences for us all. Despite an attempt to simplify the
content, some understanding of basic biology and the nervous system will help.
See terminology below.
3.
Terminology
a.
Neural plasticity - ability of
the human brain to change as a result of one’s experiences.
b.
Neurons - nerves.
c.
Neurogenesis - development of
nerve tissues.
d.
Neurotransmitter - chemical
substances which enable the nerve impulses to be passed from one nerve cell to
the next.
e.
Cognition - the mental process
of knowing, including aspects such as awareness, perception, reasoning, and
judgment.
4.
Introduction
Mens sana in corpore sano,
“a healthy mind, in a healthy body” (Juvenal 1st & 2nd
AD, Roman Poet), “give me the child until he is seven and I will give you the
man” (St Francis Xavier 1506 - 1552).
These two sayings have
been used time and again over the centuries to mean many different things.
However, I feel it is only now that their true relevance has been revealed. The
relatively modern study of developmental psychology and its link to locomotion
in the early phases of our lives is shedding new light on our evolution and enabling
us to build strategies to combat an array of conditions. More importantly it is
highlighting how we are neglecting what it is to be human; an animal that is
designed to move and interact with our environment.
This blog is only the tip
of the iceberg but touches on some of the key areas within this field of
research and what it means for you and your children.
5.
The basics
When you are born the
brain is not a finished product. It is only about 20% complete[1]. All the neurons are there, however,
they are unconnected. Over the next 3 years approximately 85% of this
connecting takes place and is believed to be completed between 6-8 years of age [1],[2]. The way in which
these neurons link however, is completely dependent on physical and emotional
experiences during these formative years [1]. You can see in Fig 1, that the synaptic connections are at their
most dense around the 2 year point and then actually thin out by the time you
are an adult. This is because the body actually over produces synaptic
connections in the early years as it lays down the foundations for later
development [2]. Following this it plateaus and then proceeds to go through a phase
of “synaptic pruning” around the age of 12 - 13yrs, where by the density of
these connections decreases to around 60%[2]. In essence this streamlines the brain to ensure it works
efficiently.
Fig 1. Showing how the
brain “wires” itself in the early years
If the brain does not
receive the correct stimulus in these formative years then it can have
detrimental effects on the way in which the brain “wires” itself, see Fig 2. Now
you may be saying to yourself “No @*%$ Sherlock, if you deprive a child of
stimulus early on then you’re going to have problems” and quite right to. But
it is not that simple;
·
How much of a problem is it?
·
How easy is it to neglect the
correct stimulus?
·
Can you re-wire the brain after
these formative years?
·
How we can we prevent it in the
first place?
The research that has been
most surprising are the effects of exercise on brain development. More and more
studies are showing that it is physical activity in these formative years that
actually lays down the pathways for learning and higher brain functions later
in life and not early introduction of “academic” style learning. The brain and
body link together to explore the environment around us, so physical activity
promotes the growth of our brains in a variety of areas, not just the parts
concerned with movement.
Fig 2. The neglected brain
6.
Exercise and Early Neural Development.
At first there was some
doubt as to the effects of exercise on the development of the brain, however,
it is now widely accepted that physical activity does stimulate brain growth [2], helps to protect new neurons and improves cognition [3].
One theory put forward for
the origin of this response to exercise is that it is possibly an adaptive
process. In our hunter gatherer past it would certainly have been advantageous
for us to engage our brains when we were foraging, i.e. improving our spatial
memory and planning abilities [3]. Whatever
the reason we know that our bodies and brains are designed to move through and engage with our environment. Not to sit at a desk all day and tap keys!
Studies
have shown that by taking regular aerobic exercise, there are marked
improvements in a child’s ability to perform in cognitive areas including
perceptual skills, creativity and concentration, academic readiness, general
achievement, IQ, maths and verbal tests [4]. This is supported by evidence
gleaned in the classroom and in the laboratory, with neuroimaging evidence
demonstrating that children with improved aerobic fitness have improved brain
function and structure in general [5].
“The
greatest cell proliferation in response to exercise occurs early in
development, suggesting that exercise interventions may be particularly
effective during early childhood” Halperin, et al (2012) [5]
Exercise
or physical activity should therefore begin as early in life as possible in
order to develop not only our bodies but more importantly our minds.
With
regard to research on resistance training and brain function in children, there
are no studies [5]. This is thought to be because of the common
misbelief that children shouldn’t undertake resistance training. As such this
area of study requires much attention.
7.
Exercise and Adult Neural Development.
Unlike in children aerobic
training has “a selective rather than general effect on task-related brain
function” [5]. This
is congruent with the fact that the adult brain has a lower degree of neural
plasticity [6]. In general, aerobic activity
increases brain structure, brain function and cognitive performance in elderly
adults [5],[6]. The
effects of resistance exercise on memory/cognition, is still very much open for
debate, with some studies showing positive results and some not [5].
However, it has to be said that regardless of its effects on memory without a
base level of strength (i.e. the strength to get out of a chair and confidently
move around) you cannot achieve aerobic fitness anyway. As such my personal
feeling is that both are important for total well being, although aerobic
fitness, at present, is the most documented for prevention and treatment of
decreasing cognitive abilities in older adults. It is important to note that stretching
and toning does not improve brain function [6].
This is significant as a large swathe of older adults who do take exercise tend
to conduct activities such as pilates and yoga (which are primarily stretching
and toning based). As this is also the population most at risk from
degenerative brain conditions, this is an area requiring some work from those
involved in this research.
8.
Conclusion
The importance of exercise
in our lives has long been acknowledged but is generally seen in a slightly superficial
way, namely to attain the “Body Beautiful” (what ever that is!!) or to improve
only the performance of our bodies from the neck down.
To me this field of
research highlights how critical physical education (P.E.), early parental
engagement and exploration of the environment is for the development of our
children, from the moment they arrive in this world. Instead the situation we
have at present couldn’t be further from this. P.E. is being cut from school
curriculums around the world, children spend more time in front of computers
and infants are bought more and more “educational toys” rather than being encouraged
to interact with the world around them. US statistics, for example, show that
less than 50% of children aged 6-11yrs get the recommended 60min of exercise
most days of the week and this figure only gets worse as they get older [5]. Then
there are the societal pressures whereby parents are smothering their children
in bubble wrap, so to speak, because they are either too scared of what might
happen to them or too scared that other people will think they are bad parents
when something does happen! The first 7 years of our children’s lives are vital
to lay down the foundations of who they are and we must encourage them to
interact with the environment and move their bodies in as many ways possible.
Fox, et al (2010) [8] sums it up nicely, “To borrow an analogy from economics, by investing early and
well in our children’s development we increase the rate of return later in
life, and in so doing improve not only the lives of individuals but of
societies as well.”
In relation to the adult
brain, the more we understand how to increase neural plasticity, the more we
can help combat a host of degenerative conditions, improve recovery following
trauma and aid conditions such as depression.
Little is known about
whether or not exercise improves cognitive abilities and memory in “normal” young
adults. Based on the research in this article however, I would hazard a guess
that physical activity is vital in order to be a healthy, well-adjusted individual.
It truly is healthy body,
healthy mind.
Regards
Gregory hunt
References
[1] Goodsport Trust Coaches Handbook, 2012. Early
Development Movement p7-8
[2] Halperin J.M., Healey D.M.The Influences of
Environmental Enrichment, Cognitive Enhancement, and Physical Exercise on Brain
Development: Can we Alter the Developmental Trajectory of ADHD? Neurosci
Biobehav Rev. 2011 January; 35(3): 621–634.
[3] Raichlen D.A., Polk J.D. Linking brains and brawn:
exercise and the evolution of human neurobiology. Proc Biol Sci. 2013 January 7; 280(1750).
[4] Voss M.W., et al. Exercise, brain, and cognition across the life span J
Appl Physiol. 2011 November; 111(5): 1505–1513.
[5] Halperin J.M., et al. Preventive
Interventions for ADHD: A Neurodevelopmental Perspective.
Neurotherapeutics. 2012 July; 9(3): 531–541
[6] Bavelier D., et
al. Removing brakes on adult brain plasticity: from molecular to behavioral
interventions. J Neurosci. 2010 November 10; 30(45): 14964–14971.
[7] Bryck R.L., Fisher P.A. Training the Brain: Practical
Applications of Neural Plasticity From the Intersection of Cognitive
Neuroscience, Developmental Psychology, and Prevention Science. Am Psychol.
2012 February; 67(2): 87–100.
[8] Fox
S.E., et al. How the Timing and
Quality of Early Experiences Influence the Development of Brain Architecture.
Child Dev. 2010 Jan-Feb; 81(1): 28–40.
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